Hydrodrive

ABSTRACT

There is disclosed a hydrodrive including a fluid-circulating drive system comprising at least two hydrounits connected by connecting conduit means with one unit being operable as a hydropump and the other unit being operable as a hydromotor. A feeding and flushing means is provided for feeding fluid media into and removing fluid media from said fluid-circulating drive system. At least one of the connecting conduit means between said hydrounits includes at least two lines and said feeding and flushing means including a feeding connection communicating with one of said lines and a flushing connection communicating with the other of said lines.

United States Patent Germany [21] Appl. No. 876,907 [22] Filed Nov. 14, 1969 [45] Patented [731 Assignees July 13, 1971 A. G. VonRoll Gerlafingen, Switzerland;

Constantin Ranch, KG

Ulm (Danbue), Germany, part interest to each [32] Priority Nov. 29, 1968 [3 3] Switzerland [3 1 1785 1/68 [54] HYDRODRIVE [50] Field of Search 60/53 A, DIG. 5

[56] References Cited UNITED STATES PATENTS 2,718,758 9/1955 Minshall et al. 60/53 A 3,040,532 6/1962 Thoma et al 60/53 A Primary ExaminerEdgar W. Geoghegan Attorney-Werner W. Kleeman ABSTRACT: There is disclosed a hydrodrive including a fluidcirculating drive system comprising at least two hydrounits connected by connecting conduit means with one unit being operable as a hydropump and the other unit being operable as a hydromotor. A feeding and flushing means is provided for feeding fluid media into and removing fluid media from said fluid-circulating drive system. At least one of the connecting conduit means between said hydrounits includes at least two lines and said feeding and flushing means including a feeding connection communicating with one of said lines and a flushing connection communicating with the other of said lines.

PATENTED JUL 1 3 mm SHEET 1 OF 3 INVENT OR Seaman Baas?- the? Chnisrinm SeN, aOuuiG waeeuseil Jonchi M FRANK ATTORNEY! PATENIED JUL 1 3 I97} SHEET 2 OF 3 INVENTOR GGRHHRD B0851", KuRT ChRisTinuscN LuDuJviG LunscnsciLJonchm Farms 13W; Mam

ATTORNEYS,

PATENTED JUL 1 3197! SHEET 3 OF 3 59 5,2 -p-jm 7 Fig.6

aJ/I/ \\\Y INVENTOR GeRunRo BossTjuaTcknisfinubw, Luowlc was seBL Jqnch'm FRANK W WMW M ATTORNEY.:

HYDRODRIVE BACKGROUND OF THE INVENTION The invention relates to a hydrodrive, comprising at least two hydrounits connected by connecting conduit means, said hydrounits being such that one works as a hydropump and the other as hydromotor, and a feed installation and flushing or exhaust installation or means for feeding and removing pres sure medium into and out of the drive circulation.

It is known to use conduit connections for feeding of fresh oil to hydrodrives which are used increasingly for the infinitely variable conversion of rotational speed, for example in vehi cles. As far as this fresh oil is concerned, it is understood to include all pressure media employed in hydrodrives of mineral, chemical or other nature and filtered and cooled, if desired, and that conduit means are likewise provided for removing used oil. These connections are located at the connecting conduit means between the pump portion comprising one or several hydropumps, and the motor portion, comprising one or several hydropumps, of the hydrodrive. It is suitable that the connection for removing oil which has circulated in the circulation of the drive be located directly at the exit of the motor portion, whereas the connection for the feeding of fresh oil for replenishing the oil which escaped during circulation as leakage loss and which has been removed to the motor portion, be located directly at the entrance to the pump portion. Both connections are thus provided successively and require a certain spacial distance between the feeding and removal for the purpose of preventing a short circuit. When the direction of power in the hydrodrive is reversed, that is to say when the motor becomes the pump, as occurs, for example, during braking or when the rotational speed is reduced, there will occur a short circuit, in that at least some fresh oil emerges again at the outlet connection of the circulation system without circulating through the hydrodrive. As a result, the thermal efficiency of this type of drive and thus the transmittable output is unfavorably influenced.

There is an increased demand for hydrodrives on account of the infinitely variable control feasibility of the output rotational speed. One endeavors on account of economical reasons, to increase more and more the unit efficiency or output of such drives. At the present time, the known hydrodrives, described as compact drives, have a specific output of about I to several kilograms per horsepower of rated output, said value being somewhat higher than that of mechanical transmissions. Also, the enclosed volume per horsepower of rated output is somewhat higher for compact drives than for mechanical step transmissions or drives. However, the differences are very slight.

In order to further increase the unit output of compact drives, one attempts to primarily increase the nominal rotational speed relative to the nominal pressure which is essentially limited by the wall thicknesses. To to this, however, one mustprovide for a sufficient feeding and flushing or exhausting in all operational conditions, as otherwise one cannot keep an increase in output under thermic control. As mentioned, the known installations for feeding and flushing, are not equally effective in all operational conditions, and they also require a certain constructional length on account of the danger of short circuiting. However, these two characteristics stand in the way ofa further increase of the unit output and a reduction of the enclosed volume.

SUMMARY OF THE INVENTION Accordingly, the present invention has for an object to provide a hydrodrive arrangement in which the feeding and flushing or exhaus ng is equally effective in all operating conditions and which is also devoid of the danger of short circuiting.

It is a particular object of the invention to provide a hydrodrive in which at least one of the connecting conduit means between the hydrounits, pump and motor, is divided into at least two lines of which one line contains the connection for flushing or exhausting and the other line contains the connection for feeding.

According to a further characteristic of the invention, the connections for feeding and flushing are disposed in a component of a hydrounit containing the control means or valve plate. Moreover, the valves for controlling the feeding and flushing can be built into the control body or valve plate of a hydrounit.

Further, as an additional object, the invention provides an arrangement in which the connections for feeding and flushing can be located in a housing wall adjoining the valve plate or control member ofa hydrounit.

According to a further characteristic of the invention, the connections for feeding and flushing, while providing the force equilibrium, can be located in the movable control member ofa hydrounit.

As another feature of the invention, the connections for feeding and flushing are disposed at equal distances from the end of the connecting conduit means. The connecting conduit means being suitably divided into at least two lines along its entire length.

Still further, in accordance with the invention, the control member can be in hydraulic equilibrium due to the position or location of and the size of the mouths of the lines of the connecting conduits in the control member.

BRIEF DESCRIPTION OF THE DRAWINGS Further and more specific objects and advantages of the invention will be readily apparent from the following description when taken in connection with the accompanying drawings in which:

FIG. I is a diagrammatic perspective view, with parts removed, illustrating a hydrodrive arrangement according to the invention and particularly showing the fluid media feeding and flushing or exhausting means of the invention;

FIG. 2 is a fragmentary longitudinal sectional view of a hydrodrive arrangement of the invention as taken along line II-II of FIG. 3;

FIG. 3 is a transverse sectional view taken along line III-III of FIG. 2;

FIG. 4 is a view similar to FIG. 3 illustrating a second embodiment of the invention and taken along line IV-IV of FIG.

FIG. 5 is a transverse sectional view taken along line V-V of FIG. 4;

FIG. 6 is a view similar to FIGS. 2 and 4 illustrating a third embodiment of the invention and taken along line VI-VI of FIG. 7;

FIG. 7 is a transverse sectional view taken along line VII-VII of FIG. 6;

FIG. 8 is a view similar to FIGS. 2, 4 and 6 illustrating a fourth embodiment of the invention and taken along line VIII-VIII of FIG. 9; and

FIG. 9 is a transverse sectional view taken along line IX-IX of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. I, the hydrounits of a hydrodrive are generally designated at 1 and 2. These units, which are only partially illustrated, are of the known axial piston type. Such units in clude a cylinder block provided with substantially parallel piston-accommodating bores, casing means within which the cylinder block is mounted for rotation, pistons within each bore, a driving means or swash plate mounted for rotation about an axis at an angle to the axis of the cylinder block and operably connected to the pistons whereby rotation of the driving means reciprocates the pistons and rotates the cylinder block. There is further included a valve plate means within the casing means engagingthe base of the cylinder block and having suitably shaped, generally segmentally shaped, admission and delivery ports adapted to register with ports in the.

cylinder block that communicate with the bores therein upon relative rotation of the cylinder block and valve plate.

Thus in FIG. 1, with only certain parts illustrated, units 1 and 2 include pistons, one for each unit being respectively shown at 3 and 4. The respective piston rods 5 and 6 are universally connected to, in this instance driving and driven discs or plates 7 and 8, respectively.

Assuming that the units are valveless, the control slots of ports 9, l0 and 11, 12 of each unit are shown. With the shown rotational directions A, B and assuming that unit 1 is driven, that is to say that it works as a hydropump, fluid medium under high pressure passes from control slot 9 to control slot 11 of hydrounit 2 which works as hydromotor where it is converted into torque at drive disc or plate 8. The relieved pres sure medium is ejected from low pressure slot 12 and reaches control slot of hydrounit 1 through connecting conduit means.

In contrast to the conventionally used single connecting conduit, the connecting conduit means between the high-pressure slots 9, 11 is divided into two lines 13, 14, and the same is done with the connecting conduit means between the lowpressure slots 10, 12, with two lines 15,16 being provided. In these lines 13,14 are located infeed connections 17,19 with the supply for the fed medium taking place through inlet conduit 23 and thereafter being connected to connections 17,19 via two one-way or nonreturn valves 21,22. The connections 18,20 for removing the circulating medium are connected between lines 14 and 16 and a flushing valve arrangement 24 in the form of a controllable two-way valve or changeover valve from whence it is discharged via outlet conduit 25.

Thus, in the case shown in FIG. 1, the feed oil into the circulation via connection 19, while circulating oil is being removed at connection 20. It can be clearly seen from the drawing that there is no danger of short circuiting in the sense that fresh oil would flow to the removal connection without circulating in the circulation system. Rather, the oil flows completely to unit 1 which works as hydropump while oil which emerges from unit 2 working as hydromotor is removed at connection 20. Since the connections 17-20 are located in the center between control slots 9-12, the feeding and flushing conditions likewise do not change if in certain operating conditions unit 2 works as hydropump and unit 1 works as hydromotor.

It can further be seen from FIG. 1 that the connecting conduits can be very short in length since it is not necessary to provide for a minimum distance between the hydrounits on account of the arrangement of the connections for feeding and flushing in different lines. Thus, it is possible to build compact drives in which the hydrounits are located practically back to back and in which the above-mentioned connections can be located in control or valve plates possessing a certain minimum thickness for reasons of rigidity, or positioned in wall portions adjoining said control or valve plates, as shown in the arrangements illustrated in FIGS. 2-9.

FIG. 2 partially illustrates a compact drive embodying two hydrounits 28,29 whose control surfaces are constructed spherically and which represent the delimitation of complementarily shaped valve plate control member 27, the latter containing the connecting conduits and the connections for feeding and flushing.

The compact drive according to FIG. 2 includes flanged housing parts 30,31 which are connected to one another by a screw or bolt arrangement, not shown in detail, at locations 32.

In FIG. 3, the same reference numerals as used in FIG. 1 identify the control slots 11,12, the connecting lines 13-16, and the connections 17-20. Two back pressure valves 33,34 in the form of spring-loaded and stem-guided valves are provided in feed connections 17 and 19, whereas the oil intake takes place through conduit 35. Numeral 36 identifies a chan geover valve which likewise consists of two spring-loaded and stem-guided valves whose guide stem means contact one another so that whichever valve is subjected to high pressure is held closed while the other valve is opened. The oil escapes via conduit 37 and flows back into the reservoir, for example, via a filter and cooler, from where it is sent back as feed oil into the circulation system by a feed pump.

The individual parts of hydrounits 28,29 will not be described in greater detail since they are generally known. The instant case deals with two inclined axis, axial piston units in which the drive shaft and the drive plate consist of one piece.

FIGS. 4 and 5 show a compact drive with hydrounits 38 and 39 in which the respective units are of different types. Unit 38 represents a so-called inclined plate or disc unit in which the drive shaft and cylinder are rigidly connected to one another, whereas the unit 39 represents a unit of the type referred to in FIG. 2. Since the control member 40 of unit 38 performs slight movements, it cannot be unified into one piece with the rigid control member or valve plate 41. For the sake of clarity, the same reference numerals have been used in FIG. 5 to denote the control slots 11,12 the connecting conduits 13-16, and for the connections 17-20. The difference, as compared with the arrangement of FIG. 3, is that the feeding valves and the flushing valves are not built into the control member, but are built on the outside of the drive housing as is indicated schematically by the dash lines in FIGS. 4 and 5 for the feed valves 42 and for flushing valve 43. The connections to conduits 17-20 is effected via short connecting ducts 44, 45, 46, 48.

FIGS. 6 and 7 illustrate a compact drive in partial view which consists of two so-called inclined plate or disc units. Since the control members or valve plates 50,51 of both units are mounted such as to be movable, the connections 17-20 for feeding and flushing are disposed in a wall 52 of the drive housing. Again, for the purpose of clarity, the reference numerals applicable to the control slots, connecting conduits and connections are the same as in FIG. 1 so that it is not necessary to describe them again. In this arrangement, the flushing valves and the feeding valve are arranged on the outside of the drive housing as in the embodiment of FIGS. 4 and 5, and they are connected to connections 17-20 by corresponding conduits 44, 45 46, 48.

In FIGS. 6 and 7, sufficient space has to be provided for connection 19 so that the housing wall 52 had to be constructed relatively thick, in any event, thicker than would be required if the only consideration had been the load factor.

FIGS. 8 and 9 illustrate that a further reduction of the wall thickness of housing wall 52 is possible if the, by and large, easily movable control member or valve plate 53 is used for the intake of the feed oil and for the removal of circulation oil. This is accomplished by providing the connections 17-20 in control member 53. The connecting conduits 55-58 to the valves being provided on the outside ofthe housing, must here be somewhat more yielding in order to prevent them from obstructing the movability of the control member 53. However, since oppositely disposed conduits always have the same pressure, there will not occur any disturbing reaction effect.

Although in FIGS. 8 and 9 the connections 17-20 are not located exactly in the center of connecting conduits 13-16, the danger of short circuiting between feeding and flushing is absent on account of the arrangement of the respective valves and different lines. The feeding and flushing effect, is in each case greater than in the known constructions, and there is furthermore obtained a substantial saving of space. A further advantage is that in hydrounits in which the control member is movably maintained in hydraulic equilibrium, this equilibrium is achieved by a suitable arrangement of and/or dimensioning of the partial lines without making it necessary that the control member be provided with additional support systems. As a result, the control member alone can be dimensioned for the occurring loads without having to give consideration for the space requirements of support pistons, thus enabling further coherence of the units.

The use of the instant invention is not limited to valveless hydrounits, but it can be used in all hydrounits, that is to say, not only in compact drives, but also in overdrives, for the prevention of short circuiting between feeding and flushing. Where there are longer connecting conduits, only a part of the conduit need be divided into individual lines for the separate provision of feeding and flushing.

It should be apparent from the foregoing detailed description, that the objects set forth at the outset to the specification have been successfully achieved.

What we claim is:

l, A hydrodrive including a fluid-circulating drive system, comprising at least two hydrounits connected by connecting conduit means of which one unit is operable as a hydropump and the other unit is operable as a hydromotor, and a feeding and flushing means for feeding fluid media into and removing fluid media from said circulating drive system, at least one of the connecting conduit means between said hydrounits including at least two lines, and said feeding and flushing means including a feeding connection communicating with one of said lines and a flushing connection communicating with the other of said lines.

2. A hydrodrive as claimed in claim 1, including hydrounit control means having a control member and said feeding and flushing connections being disposed in said control member.

3. A hydrodrive as claimed in claim 2 and further including valve means for controlling flow of fluid media through said feeding and flushing connections also disposed in said control member.

4. A hydrodrive as claimed in claim 1 including casing means for said hydrounits, hydrounit control means having a control member, said casing means including a wall portion surrounding said control member and said feeding and flushing connections being disposed in said wall portion.

5. A hydrodrive as claimed in claim 1 including hydrounit control means having a movable control member and said feeding and flushing connections being disposed in said movable control member.

6. A hydrodrive as claimed in claim I and said feeding and flushing connections being disposed at the same distance from the ends of said connecting conduit means.

7. A hydrodrive as claimed in claim 2 and said feeding and flushing connections being disposed at the same distance from the ends of said connecting conduit means.

8. A hydrodrive as claimed in claim 4 and said feeding and flushing connections being disposed at the same distance from the ends of said connecting conduit means.

9. A hydrodrive as claimed in claim 1 and said connecting conduit means including high and low pressure accommodating conduit means each including at least two lines.

[0. A hydrodrive as claimed in claim 1 including hydrounit control means having at least one control member, said connecting conduit means and said feeding and flushing connections being disposed in said control member and the location of and size of the areas of communication of said connecting conduit means with said connections being such as to maintain said control member in hydraulic equilibrium.

1]. A hydrodrive comprising at least two units having a fluid circulating system including at least two conduit means con necting said units and so arranged that one unit is operable as a pump and the other is operable as a motor, means for feeding fluid media into and removing fluid media from said circulating system, at least one of said conduit means comprising at least two lines extending between said units, and said means for feeding fluid into and removing fluid media from said circulating system including a fluid-feeding connection communicating with one of said lines and a fluid-removing connection communicating with the other of said lines.

12. A hydrodrive as claimed in claim 11 and each hydrounit including segmentally shaped fluid admission and delivery ports, said conduit means comprising a pair of fluid-accommodating lines extending between the delivery port of one unit and the admission port of the other unit, another pair of fluidaccommodating lines extending between the delivery port of said other unit and the admission port of said one unit, and

said fluid-feeding connection and fluid-removing connection each communicating with a fluid-accommodating line of at least one of said pairs of fluid-accommodating lines.

13. A hydrodrive as claimed in claim 12 and a fluid-feeding connection and a fluid-removing connection each communicating with a fluid-accommodating line of the other pair of fluid-accommodating lines. I

14. A hydrodrive as claimed in claim 13 and nonretum valve means operably associated with each fluid-feeding connection and pressure-responsive shiftable valve means operably associated with said fluid-removing connections. 

1. A hydrodrive including a fluid-circulating drive system, comprising at least two hydrounits connected by connecting conduit means of which one unit is operable as a hydropump and the other unit is operable as a hydromotor, and a feeding and flushing means for feeding fluid media into and removing fluid media from said circulating drive system, at least one of the connecting conduit means between said hydrounits including at least two lines, and said feeding and flushing means including a feeding connection communicating with one of said lines and a flushing connection communicating with the other of said lines.
 2. A hydrodrive as claimed in claim 1, including hydrounit control means having a control member and said feeding and flushing connections being disposed in said control member.
 3. A hydrodrive as claimed in claim 2 and further including valve means for controlling flow of fluid media through said feeding and flushing connections also disposed in said control member.
 4. A hydrodrive as claimed in claim 1 including casing means for said hydrounits, hydrounit control means having a control member, said casing means including a wall portion surrounding said control member and said feeding and flushing connections being disposed in said wall portion.
 5. A hydrodrive as claimed in claim 1 including hydrounit control means having a movable control member and said feeding and flushing connections being disposed in said movable control member.
 6. A hydrodrive as claimed in claim 1 and said feeding and flushing connections being disposed at the same distance from the ends of said connecting conduit means.
 7. A hydrodrive as claimed in claim 2 and said feeding and flushing connections being disposed at the same distance from the ends of said connecting conduit means.
 8. A hydrodrive as claimed in claim 4 and said feeding and flushing connections being disposed at the same distance from the ends of said connecting conduit means.
 9. A hydrodrive as claimed in claim 1 and said connecting conduit means including high and low pressure accommodating conduit means each including at least two lines.
 10. A hydrodrive As claimed in claim 1 including hydrounit control means having at least one control member, said connecting conduit means and said feeding and flushing connections being disposed in said control member and the location of and size of the areas of communication of said connecting conduit means with said connections being such as to maintain said control member in hydraulic equilibrium.
 11. A hydrodrive comprising at least two units having a fluid circulating system including at least two conduit means connecting said units and so arranged that one unit is operable as a pump and the other is operable as a motor, means for feeding fluid media into and removing fluid media from said circulating system, at least one of said conduit means comprising at least two lines extending between said units, and said means for feeding fluid into and removing fluid media from said circulating system including a fluid-feeding connection communicating with one of said lines and a fluid-removing connection communicating with the other of said lines.
 12. A hydrodrive as claimed in claim 11 and each hydrounit including segmentally shaped fluid admission and delivery ports, said conduit means comprising a pair of fluid-accommodating lines extending between the delivery port of one unit and the admission port of the other unit, another pair of fluid-accommodating lines extending between the delivery port of said other unit and the admission port of said one unit, and said fluid-feeding connection and fluid-removing connection each communicating with a fluid-accommodating line of at least one of said pairs of fluid-accommodating lines.
 13. A hydrodrive as claimed in claim 12 and a fluid-feeding connection and a fluid-removing connection each communicating with a fluid-accommodating line of the other pair of fluid-accommodating lines.
 14. A hydrodrive as claimed in claim 13 and nonreturn valve means operably associated with each fluid-feeding connection and pressure-responsive shiftable valve means operably associated with said fluid-removing connections. 